Flexible pipe and coupling therefor

ABSTRACT

Embodiments of the invention relate to the construction of a sealed connection between an elastomeric or synthetic polymer flexible pipe or hose and a metallic coupling member. The coupling member surrounds an armour layer at a free end of the flexible pipe or hose. A sealing area is defined by a recessed portion of the pipe coupling into which a sealing material is introduced. An inner layer of the flexible pipe or hose may extend into the sealing area where it is bonded to the sealing material. The sealing material and the inner liner layer may each be comprised of a semi-crystalline thermoplastic material. Furthermore, a reinforcement material is provided in the inner layer.

TECHNICAL FIELD

The present invention relates to a flexible pipe or hose for highpressure or high pressure/high temperature applications andparticularly, though not exclusively, to the construction of a sealedconnection between the pipe or hose and a metallic coupling member. Inone embodiment of the invention, a reinforcement means is incorporatedinto an inner liner of the flexible pipe or hose. The flexible pipe orhose of the present invention is primarily intended to be suitable forthe transportation of hydrocarbon liquids or gases and/or water. Alsodisclosed are methods for manufacturing a flexible pipe or hose havingthe aforementioned characteristics. Whilst the terms “pipe” and “hose”are generally used synonymously throughout the present disclosure, apipe may be understood as being relatively less flexible than a hosewhere the context so allows.

BACKGROUND OF THE INVENTION

Flexible pipes or hoses are used in both onshore and offshoreapplications in the field of oil & gas exploration primarily for thetransportation of fluids and gases. The term “flexible” is to beunderstood to exclude substantially rigid constructions, such as steelpipes. Flexible pipes or hoses are typically used to transportpressurised, high temperature crude oil and gas from a seabed basedwellhead to a floating platform or processing facility. However, theyare equally suitable for carrying a wide range of injection or servicefluids aimed at enhancing or maintaining production output.Consequently, flexible pipes hoses are exposed to wide variations inboth internal & external pressure and temperature.

Typical pipe or hose pressure and temperature ratings are disclosed in,e.g., American Petroleum Institute (API) standard 7K—5th Edition—June2010, tiled ‘Drilling and Well Servicing Equipment’ (see paragraphs9.6.1, 9.6.3.1 and Table 9). Further guidance on the pressure and/ortemperature conditions experienced in flexible pipes or hoses (typicallyof diameter of 3″ and above) can be found in API standards, 16C (seeTables 3.4.1, 3.4.2, 3.4.3 and 3.5.2.1), OCIMF, 171 and 17K. In moderatediameter hoses the pressure rating will typically be several hundred bar(e.g. of the order of 10 to over 100 MPa.), and will decrease withincreasing hose diameter. Flexible pipes or hoses must be able towithstand typical temperature conditions of approximately −40° C. to+132° C. depending upon the application.

Flexible pipes can be divided into two categories: bonded and unbonded.Unbonded flexible pipes typically comprise a number of metallic armourlayers and polymeric anti-wear/anti-friction layers whereby a degree ofrelative slippage between at least two adjacent layers is possible. Evenwhere one layer is embedded within another, the non-bondedcharacteristics can be demonstrated by a simple pull out test of, forexample, a steel cord reinforcement layer out of its surrounding polymermatrix. This test is based on an adapted version of the ‘Standard TestMethod for Rubber Property—Adhesion to Steel Cord’ (ASTMD 2229-85)′.

Bonded pipes—which are commonly used for a range of similar applicationsas non-bonded pipes—preclude any slippage between adjacent layers.Bonded pipes employ either an inner elastomeric or thermoplastic linerpipe that is sometimes extruded on or bonded to an underlying metalcarcass and surrounded by an armour layer. The entire pipe can beconsidered to be a composite of bonded metal cable or wire (eitherbrass-coated or galvanised) and elastomeric layers, with the possibleinclusion of a thermoplastic inner liner layer as noted below. Bondedpipes are tested to ensure that they are capable of withstanding rapidgas decompression events which can cause a blistering phenomenon intheir innermost layers. Bonded flexible pipe types can be used asflexible risers, loading hoses or hoses for exploration (rotary hoses,choke & kill hoses, mud & cement hoses).

In order to avoid liquid and gas permeation losses, a thermoplasticpipe—or a pipe having a thermoplastic inner liner—is often employed soas to enhance its overall sealing ability. However, some fluids or gasescan be very aggressive and cause rapid degradation of certain polymersor plastics liners, especially at higher temperatures. To address thisproblem, it is known to employ more chemically inert polymer typeswithin the pipe and/or its inner liner (if present) such as cross-linkedpolyethylene (PEX), polyamide 11/12 (PA11/PA12), ethylenetetrafluoroethylene (ETFE), polyvinylidene fluoride (PVDF) or polyetherether ketone (PEEK). Whilst these engineered polymers offer manyadvantages in terms of temperature resistance, sour corrosionresistance, anti-cracking behaviour, low gas/liquid permeability etc.,they are known to be less effective in ensuring a good quality seal witha hose coupling (i.e. either a pipe-to-pipe or pipe-to-end-fittingconnection). Often these liners are reinforced with an inner (stainlesssteel) carcass.

To ensure a reliable seal between a pipe, or an inner liner thereof, anda coupling (i.e. either a pipe-to-pipe or pipe-to-end-fittingconnection) all ‘leakage paths’ must be eliminated. A leakage path isany path allowing pressurized fluid or gas to equalise with a lowerpressure state. Fabrics, air pockets, armouring cables or any continuousbonding failure between adjacent layers or materials within the pipeconstruction can all give rise to such a ‘leakage path’ causinglocalised gas/liquid accumulations leading to blistering and,ultimately, failure of the flexible pipe. A secure and effective seal isa fundamental safety requirement for high pressure, high temperaturebonded pipes. To the best knowledge of the inventor, all manufacturersof bonded hoses have to date employed an elastomer-based sealingcompound, e.g. such as that disclosed in GB2329439B (Antal et al).

Elastomers constitute the most flexible, deformable and elastic of thethree classes of the non-metallic polymer materials. A behaviouralcharacteristic of all elastomers is that they are inherently permeableto gases and vapours. When used within a flexible pipe for hightemperature/high pressure applications, transmission of dissolved gasesinto microvoids within the elastomeric structure make the pipe moreprone to rupture during a rapid depressurisation event, i.e. wherebybubbles form within the microvoids when pressure externally of the pipeis lost. This type of pipe failure is known as ‘explosive decompression’and results in a catastrophic failure of the pipe seal and/or lining.

In an effort to minimise instances of ‘explosive decompression’,flexible pipes for high temperature/high pressure applications typicallyemploy an inner thermoplastic liner to reduce the likelihood ofliquid/gas permeation; and an inner strip-wound steel carcass locatedradially inside the thermoplastic liner to reduce the likelihood ofblistering. Whilst such preventative measures are generally effectivealong the length of a pipe, the sealed connection between a pipe and itscoupling (i.e. either a pipe-to-pipe or pipe-to-end-fitting connection)is an area which remains the subject of sealing stresses. Such stressesarise from mechanically applied compression and/or compression arisingfrom the hydrostatic pressure of the fluid being sealed.

In terms of their functional properties, elastomers are soft,substantially elastic, and substantially incompressible. Suchcharacteristics make elastomers suitable for use as primary seals at theinterface of a pipe and its coupling. The inherent incompressibility ofelastomers means that high stresses can be resisted, and high pressurescan be accommodated, when the elastomer material is highly constrained.Elastomeric seals are therefore an automatic choice for hightemperature/high pressure applications. Nevertheless, several modes ofelastomeric failure or deterioration are well documented, as summarisedin Tables 1 and 2 in the Health & Safety Executive Report No. 320 (2005)titled: ‘Elastomers for fluid containment in offshore oil and gasproduction: Guidelines and review’ (ISBN 0 7176 2969 4). In Table 1, afailure mode of “Rapid gas decompression or explosive decompression(ED)” is described as follows: “Gas dissolved in the elastomer underhigh pressure conditions comes out of solution and forms bubbles in thematerial when the external pressure is lost. The bubbles may growsufficiently to cause fracture of the material (e.g. seals) or of aninterface (e.g. between the liner and adjacent layer in a hose).

In view of the known modes of elastomeric failure or deterioration, onlyone of which is described above, the present inventor has concluded thatthere is a requirement for alternative flexible pipe arrangementsproviding a recognisable improvement over current sealing performancewhilst simplifying overall pipe construction and methods of manufacture.In particular, further improvements in terms of the ability of aflexible pipe or hose and any associated coupling to withstand hostileconditions, over a longer period, would be highly desirable.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda synthetic polymer flexible pipe comprising:

-   -   (i) an armour layer surrounding an end of the flexible pipe;    -   (ii) a pipe coupling disposed at the end of the pipe and        surrounding the armour layer;    -   (iii) a sealing area defined by a recessed portion of the pipe        coupling; and    -   (iv) a sealing material disposed in the sealing area;        wherein said pipe end extends into the sealing area and is        bonded to the sealing material, and characterised in that the        sealing material is non-elastomeric and both the sealing        material and the flexible pipe comprise the same class of        synthetic polymer selected from the group comprising        thermoplastics and thermosets.

Optionally, the flexible pipe and the sealing material each comprise asemi-crystalline thermoplastic material.

In one embodiment, the sealing material is provided as an injectablefluid or molten synthetic polymer.

In an alternative embodiment, the sealing material is provided as asolid meltable seal.

Optionally, the solid meltable seal comprises metallic particlesselected from one or more the group comprising: fibres, coarse grains,chips, or fine powder.

Optionally, different sizes of metallic particles are distributedthroughout the solid meltable seal.

Optionally, only an inner liner layer of the flexible pipe comprises asemi-crystalline thermoplastic material which extends into the sealingarea.

Optionally, a reinforcement material is provided within the inner linerlayer but is not bonded to its semi-crystalline thermoplastic material.

Alternatively, a reinforcement material is provided within the innerliner layer which is fully bonded to its semi-crystalline thermoplasticmaterial by means of an adhesive tie layer.

Optionally, the reinforcement material comprises helically wound steelcord and/or steel wires.

Optionally, two or more separate helically wound steel cord and/or steelwires are arranged in an interlocking fashion.

Optionally, the reinforcement material is arranged within the innerliner layer in a wound fashion at an angle of between 25 degrees and 85degrees relative to the longitudinal axis of the flexible pipe.

Optionally, the reinforcement material comprises one or more fibrestrands and/or rovings selected from the list comprising: glass fibres,carbon fibres, UHmwPE (ultra high molecular weight polyethylene) fibresand aramid fibres.

Optionally, an electrical heating element is provided within the innerliner layer.

Optionally, the electrical heating element comprises one or morematerials selected from the list comprising: conductive wires,conductive cables, conductive fabrics or conductive composites.

Optionally, the semi-crystalline thermoplastic material of the innerliner layer is directly bonded to the semi-crystalline thermoplasticmaterial of the sealing material by a polymer-to-polymer bond.

Optionally, the semi-crystalline thermoplastic material of the sealingmaterial is directly bonded to the pipe coupling by a polymer-to-metalbond.

Alternatively, the semi-crystalline thermoplastic material of thesealing material is indirectly bonded to the inner liner layer and/orthe pipe coupling via an intermediate adhesive tie layer.

Optionally, the adhesive tie layer also comprises a semi-crystallinethermoplastic material.

Optionally, the semi-crystalline thermoplastic material of the innerliner layer and/or sealing material is a polyvinylidene fluoride (PVDF)material.

Alternatively, the semi-crystalline thermoplastic material of the innerliner layer and/or sealing material is a cross-linked polyethylene (PEX)material.

Alternatively, the semi-crystalline thermoplastic material of the innerliner layer and/or sealing material is a perfluoroalkoxy (PFA) material.

Optionally, the pipe coupling is formed from a metal or a metal alloy.

Optionally, a cylindrical sleeve member is disposed beneath the innerliner at the end of the flexible pipe and cooperates with the pipecoupling proximate the sealing area to support a portion of the innerliner layer extending into the sealing area.

Optionally, an outer surface of the cylindrical sleeve member isinclined at an acute angle relative to the central longitudinal axis ofthe pipe.

Optionally, the inner liner layer is coupled to the pipe coupling by acrimped or swaged connection.

According to a second aspect of the present invention, there is provideda method of manufacturing a synthetic polymer flexible pipe, comprisingthe steps of:

-   -   (i) providing a pipe coupling comprising a recessed portion        defining a sealing area;    -   (ii) providing a flexible pipe and an armour layer surrounding        the pipe;    -   (iii) providing a sealing material for introduction into the        sealing area;    -   (iv) fitting the pipe coupling to the end of the hose; and    -   (v) establishing a permanent polymer-to-polymer and        polymer-to-metal chemical bond within the sealing area between        said pipe end and the sealing material; and the pipe coupling        and the sealing material respectively;        wherein the sealing material is non-elastomeric and both the        sealing material and at least a portion of the flexible pipe are        composed of the same class of synthetic polymer selected from        the group comprising thermoplastics and thermosets.

Optionally, the method includes the further step of providing areinforcement means within the flexible pipe.

Optionally, a supporting member is introduced beneath an inner surfaceof said pipe end before or after the step of fitting the pipe couplingto the pipe end.

In one embodiment, the supporting member is introduced prior to fittingthe pipe coupling so as to expand the diameter of the pipe end, theexpanded portion being supported proximate the sealing area once thepipe coupling is fitted.

Optionally, the step of establishing a permanent chemical bond withinthe sealing area involves introducing the sealing material into thesealing area by injection through a passage linking the sealing area tothe exterior of the pipe coupling.

In an alternative embodiment, the step of establishing a permanentchemical bond within the sealing area involves introducing the sealingmaterial into the sealing area by mounting a solid meltable seal ontothe pipe, proximate the pipe end, before fitting the pipe coupling tothe pipe end.

Optionally, the step of fitting the pipe coupling to the pipe end isfollowed by the step of introducing the supporting member beneath aninner surface of said pipe end, the supporting member incorporating aheater which melts the solid meltable seal within the sealing area.

Optionally, the step of introducing the supporting member involvesemploying an inflatable supporting member which is temporarily inflatedagainst the inner surface of said pipe end whilst the permanent chemicalbond is established.

Alternatively, the step of introducing the supporting member is followedby permanently swaging it against the inner surface of said pipe end.

Optionally, the step of melting the solid meltable seal within thesealing area is accompanied by the step of applying a vacuum to removesubstantially all air from the sealing area.

Optionally, the steps of providing a flexible pipe and providing asealing material each include providing a pipe and sealing materialcomprising a semi-crystalline thermoplastic material.

Optionally, the step of establishing a permanent chemical bond involvescooling the sealing material.

According to a third aspect of the present invention, there is providedan elastomeric flexible hose comprising:

-   -   (i) a semi-crystalline thermoplastic inner liner layer;    -   (ii) an armour layer surrounding the inner liner layer at an end        of the flexible hose;    -   (iii) a hose coupling disposed at the end of the hose and        surrounding the armour layer;    -   (iv) a sealing area defined by a recessed portion of the hose        coupling; and    -   (v) a semi-crystalline thermoplastic sealing material, or a        cross-linked elastomeric sealing material, disposed in the        sealing area;        wherein a portion of the inner liner layer at said hose end        extends into the sealing area and is bonded to the sealing        material, and characterised in that a reinforcement material is        provided within the inner liner layer.

Optionally, the reinforcement material is not bonded to thesemi-crystalline thermoplastic material.

Optionally, the reinforcement material comprises helically wound steelcord and/or steel wires.

Optionally, two or more separate helically wound steel cord and/or steelwires are arranged in an interlocking fashion.

Optionally, the reinforcement material is arranged within the innerliner layer in a wound fashion at an angle of between 25 degrees and 85degrees relative to the longitudinal axis of the flexible hose.

Optionally, the reinforcement material comprises one or more fibrestrands and/or rovings selected from the list comprising: glass fibres,carbon fibres, UHmwPE, (ultra high molecular weight polyethylene) fibresand aramid fibres.

Optionally, an electrical heating element is provided within the innerliner layer.

Optionally, a cylindrical sleeve member is disposed beneath the innerliner at the end of the flexible hose and cooperates with the hosecoupling proximate the sealing area to support a portion of the innerliner layer which extends into the sealing area.

In one embodiment, the sealing material is provided as an injectablefluid or molten synthetic polymer.

In an alternative embodiment, the sealing material is provided as asolid meltable seal.

Optionally, the solid meltable seal comprises metallic particlesselected from one or more the group comprising: fibres, coarse grains,chips, or fine powder.

Optionally, different sizes of metallic particles are distributedthroughout the solid meltable seal.

Optionally, the inner liner layer is coupled to the hose coupling by acrimped or swaged connection.

Optionally, all adjacent layers of the flexible hose are partially orfully bonded in a permanent connection.

Optionally, an outer cover layer surrounds the armour layer andcomprises a semi-crystalline thermoplastic material.

Optionally, a reinforcement material is provided within the outer coverlayer.

Optionally, the reinforcement material comprises one or more materialsselected from the list comprising steel cord, steel strands, fibrestrands and fibre rovings.

Optionally, the fibre strands or rovings comprise one or more fibresselected from the list comprising glass fibres, carbon fibres, UHmwPE(ultra high molecular weight polyethylene) fibres and aramid fibres.

Optionally, the reinforcement material within the outer cover is alignedin a uni-directional, bi-directional or multi-directional manner.

Optionally, the reinforcement material within the outer cover layer isprovided within a fabric or a plied tape.

Optionally, a stainless steel interlock cover layer surrounds theexterior of the flexible hose.

According to a fourth aspect of the present invention, there is provideda method of manufacturing an elastomeric flexible hose, comprising thesteps of:

-   -   (i) providing a hose coupling comprising a recessed portion        defining a sealing area;    -   (ii) providing a hose comprising a semi-crystalline        thermoplastic inner liner layer, and an armour layer surrounding        the inner liner layer at an end of the flexible hose;    -   (iii) providing a semi-crystalline thermoplastic sealing        material, or a cross-linked elastomeric sealing material, for        introduction into the sealing area;    -   (iv) providing a reinforcement material within the inner liner        layer;    -   (v) fitting the pipe coupling to the end of the hose; and    -   (vi) establishing a permanent chemical bond within the sealing        area between the hose end and the sealing material; and the hose        coupling and the sealing material respectively.

Optionally, the step of establishing a permanent chemical bond withinthe sealing area involves introducing the sealing material into thesealing area by mounting a solid meltable seal proximate the hose endbefore fitting the hose coupling to the hose end.

Optionally, the step of fitting the hose coupling to the hose end isfollowed by the step of introducing a supporting member beneath an innersurface of said hose end, the supporting member incorporating a heaterwhich melts the solid meltable seal within the sealing area.

Optionally, the step of introducing the supporting member involvesemploying an inflatable supporting member which is temporarily inflatedagainst the inner surface of said hose end whilst the permanent chemicalbond is established.

Alternatively, the step of introducing a supporting member is followedby permanently swaging it against the inner surface of said hose end.

Optionally, the step of melting the solid meltable seal within thesealing area is accompanied by the step of applying a vacuum to removesubstantially all air from the sealing area.

Use of the words “preceded by”, “followed by”, “before”, “after” are notnecessarily intended to mean immediately “preceded by” etc., unless thecontext so demands.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional schematic view showing a pipe or hosecoupling fitted over the end of a flexible pipe or hose;

FIG. 2 a is a cross-sectional schematic view showing the sealing area ofFIG. 1 in more detail;

FIG. 2 b is a cross-sectional schematic view showing the sealing area ofFIG. 2 a filled with a non-elastomeric sealing material;

FIG. 3 a is a cross-sectional schematic view showing an alternativesealing area allowing for more mechanical grip;

FIG. 3 b is a cross-sectional schematic view showing the alternativesealing area of FIG. 3 a filled with a non-elastomeric sealing material;

FIG. 4 a is a cross-sectional schematic view showing the lay angle ofreinforcement within the inner liner;

FIG. 4 b is a cross-sectional schematic view showing an alternative layangle and a heating means within the inner liner;

FIG. 5 is a cross-sectional schematic view showing a hose couplingfitted over the end of a flexible pipe or hose having an alternativeouter reinforcement structure;

FIG. 6 is a cross-sectional schematic view showing a pipe or hosebuild-up whereby the constituent layers have been progressively strippedback towards the pipe/hose end in preparation for fitting a pipe/hosecoupling thereto;

FIG. 7 is a cross-sectional schematic view showing a pipe or hosebuild-up of FIG. 6 with a meltable sealing ring mounted to its free end;

FIG. 8 a is a cross-sectional schematic view showing a pipe or hosecoupling fitted over the end of the meltable sealing ring of FIG. 7;

FIG. 8 b is a cross-sectional schematic view showing a pipe or hosecoupling fitted over the end of an alternative L-shaped meltable sealingring;

FIG. 9 is a cross-sectional schematic view corresponding to FIG. 8 ashowing a supporting member incorporating an induction heater;

FIG. 10 is a cross-sectional schematic view corresponding to FIG. 8 ashowing the establishment of chemical bond in the sealing area afterremoval of the supporting member shown in FIG. 9;

FIG. 11 a is a cross-sectional schematic view showing the sealing areaof FIG. 8 a in more detail;

FIG. 11 b is a cross-sectional schematic view showing the sealing areaof FIG. 10 in more detail.

FIG. 12 a is a cross-sectional schematic view showing the sealing areaof FIG. 8 b in more detail prior to activation of an induction heater;and

FIG. 12 b is a cross-sectional schematic view showing the sealing areaof FIG. 8 b in more detail after activation of an induction heater.

FIG. 1 shows a schematic cross-sectional view of an end of a flexiblehose surrounded by an annular hose coupling 13. The innermost layer ofthe flexible hose is a semi-crystalline polymer inner liner 1 withinwhich is embedded a reinforcement material 2. In some embodiments (notshown) a flexible stainless steel interlock or carcass may be disposedradially within (i.e. beneath) the inner liner 1 and chemically bondedor crimped thereto to form the innermost layer.

The inner liner 1 may be formed from any suitable type of semicrystalline thermoplastic, e.g. polymers derived from polyolefins.Possible options include, but are not necessarily limited to:polypropylene; fully or partially cross-linked polyethylene; polyamidessuch as polyamide-polyimide; polyimide (Pi) (PA6, PA11 or PA12);polyurethanes (PU); polyureas; polyesters; polyacetals; polyethers suchas polyethersulphone (PES), polyoxides; polysulfides such aspolyphenylene sulphide (PPS); polysulphones such as polyarylsulphone(PAS); polyacrylates; polyethylene terephtalate, (PET);polyether-ether-ketones (PEEK); polyvinyls; polyacrylonitrils;polyeterketoneketone (PEKK). Further options include co-polymers of theforegoing such as fluorous polymers; tomo-polymers or copolymers of, forexample, trifluorethylene (VF3) or tetrafluoroethylene; coplolymers orterpolymers comprising two or more different members selected from VF2,VF3, chlorotrifluorethylene, tetrafluoroethylene, hexafluoropropene orhexafluoroethylene; polymer blends comprising one or more of the abovementioned polymers and composite materials, such as an abovementionedpolymer compounded with reinforcement fibres such as glassfibers and/orcarbon fibers and/or aramid fibers. The choice of semi crystallinethermoplastic for a given application will depend on the specificexpected service conditions of the flexible pipe and perhaps otherconsiderations such as ease of manufacture and cost.

The inner liner 1 is surrounded by a consolidating fabric layer 8. Thefabric layer 8—which may include rubber—is surrounded by a steel sleeve7 which increases in thickness towards the end of the flexible hose. Thesteel sleeve 7 is surrounded by one or more armour layers 9 comprisingof, for example, one or more helically wound layers of steel cord, steelwires or glass/carbon/aramid fibre strands or rovings embedded within arubber cushioning layer 10. The armour layers 9 and cushioning layers 10may be provided in the form of tape which is wound around the innerliner 1 in one or more plies. Different plies may be wound at differentwinding angles. If present, the reinforcement material 2 within theinner liner 1 may take the form of helically wound steel cord, steelwires or fibre strands or rovings with a winding angle of between 25degrees and 85 degrees relative to the longitudinal axis 100 of theflexible hose (see FIG. 4 a). Preferably, the winding angle will be asclose as possible to the neutral angle of 54-55 degrees. The windingangle may be adjusted depending on particular requirements. However, thewinding angle will normally not be less than 25 degrees or more than 85degrees to ensure controlled bending behaviour. Exceptionally, thewinding angle may be less than 25 degrees if the application requiresthe inner liner 1 to be collapsible (see FIG. 4 b). In that specificcase the embedded reinforcement layers act as a stiffener for the innerliner 1 limiting the elongation to a value of less than the elongationthreshold of the inner liner's thermoplastic material. In oneembodiment, one or more additional layers of the same reinforcementmaterial 2 may be would at different angles with compatiblethermoplastic materials over-extruded to fully embed the respectiveadditional reinforcement layers.

The steel cord and/or steel wires may be wound such that adjacentwindings are interlocked. The reinforcement material 2 may also comprisefibre strands and/or rovings selected from the list comprising: glassfibres, carbon fibres, UHmwPE (ultra high molecular weight polyethylene)fibres (Dyneema) and aramid fibres. It will be understood that this listis non-exclusive. The reinforcement material may be a textile weave orfabric made up of one or more of the aforementioned materials. Thereinforcement material 2 may be provided in the form of a tapecontaining one or more of the abovementioned materials. Thereinforcement material 2 may be over-extruded with the samesemi-crystalline thermoplastic material from which the inner liner 1 ismade. It is preferable that the reinforcement material 2 may accommodateshear deformation caused by the application of loads, e.g. duringbending. Accordingly, the reinforcement material 2 is optionally notbonded to the thermoplastic material of the inner liner 1 within whichit is embedded.

A source of heat may be incorporated into the inner liner 1, for exampleby adding an electric heat tracing layer above and/or below and/oramongst the reinforcement material 2 (also shown in FIG. 4 b). It isessential that the generated heat is maintained well below the meltingpoint of the thermoplastic material of the inner liner 1. The heattracing elements may comprise separate conductive wires or utilise thesteel cables or steel based fabrics or composite materials of thereinforcement material 2 itself.

The internal diameter of the annular hose coupling 13 increases in agenerally stepwise fashion from left to right as viewed in FIG. 1. Arecessed portion 3 is provided at one end of the body of the hosecoupling 13 nearest its narrowest internal diameter. The term “recessedportion” is to be understood in this context as defining the innerenlarged diameter space bounded by the hose coupling body, thecylindrical sleeve 6, and the innermost layers 1, 8 of the flexiblehose, i.e. as indicated with the closely spaced diagonal shading inFIGS. 1 and 5.

The end portion of the flexible hose is prepared to receive the hosecoupling in a conventional manner, for example by curing and strippingback to progressively expose its underlying layers. A cylindrical innersleeve 6 is disposed within the end portion of the flexible hose. Theinternal diameter defined by the inner sleeve 6 is selected so as to besubstantially equal to the internal diameter of the flexible hosedefined by its inner liner 1. The outer surface of the inner sleeve 6tapers towards the longitudinal axis 100. As the inner sleeve 6 isinserted into the end of the flexible hose its tapered portion(s) engagethe innermost surface of the inner liner 1. Progressive insertion of theinner sleeve 6 into the flexible hose causes the internal diameter ofthe inner liner 1 to expand as it is forced up the tapered surface(s) ofthe inner sleeve 6.

The recessed portion 3 of the hose coupling 13 is partially closed bythe inner sleeve 6 when the hose coupling is fitted over the expandedend of the flexible hose. Once positioned over its end, the hosecoupling may optionally be crimped onto the flexible hose from theoutside. An epoxy resin 11 is introduced—via end caps 12—into the areabetween the inner surface of the hose coupling body 13 and the strippedback layers of the flexible hose.

Once the hose coupling is in place, the inner sleeve 6 thereforesupports the expanded end portion of the inner liner 1 within therecessed portion 3 of the hose coupling body 13 together with an end ofthe surrounding fabric layer 8 and steel sleeve 7. All three layers arecompressed—for example by crimping or swaging from the inside—betweenthe outer surface of the inner sleeve 6 and an opposing surface of thehose coupling body 13 in a manner which closes off the path between therecessed portion 3 and the internal cylindrical volumes of the flexiblehose and the coupling body 13.

The internal volume of the recessed portion 3—hereinafter “the sealingarea”—is bounded by the inner wall of the coupling body 13 and—in apreferred embodiment—the radial outer surface of the inner sleeve 6. Onesurface portion of the inner wall of the coupling body 13 is inclined atan acute angle relative to the longitudinal axis 100 of the flexiblehose. The acute angle may be approximately 45 degrees. An end portion ofthe flexible hose—i.e. its inner liner 1 and fabric layer 8—extends intothe sealing area 3 as shown in greater detail in FIG. 2 a.

FIGS. 3 a and 3 b show an alternative sealing area 3 whereby the innerwall of the coupling body 13 and the radial outer surface of the innersleeve 6 are provided with a serrated surface profile 16. The serrations16 provide an enhanced mechanical connection between the surfaces withinthe sealing area 3 and the sealing material 15. As shown in FIG. 3 b,the presence of the serrations 16 may mean that the tie layer 14 needonly be applied to any non-serrated surfaces within the sealing area 3.One surface portion of the inner wall of the coupling body 13 within thesealing area 3 is inclined at an obtuse angle relative to thelongitudinal axis 100 of the flexible hose. The obtuse angle may beapproximately 135 degrees. This serves to increase the surface area ofthe sealing bond between the sealing material 15 and the coupling body13 and hence further strengthens the bond.

A passage is provided through an exterior surface of the hose couplingbody 13 to provide access to the sealing area 3 via a removable end cap5. In one embodiment, a non-elastomeric sealing material can beintroduced into the sealing area 3 through the passage using a built-innipple connector 4. As shown in FIG. 2 b, the sealing material 15completely fills the sealing area 3 and may be cured to establish apermanent polymer-to-polymer and polymer-to-metal chemical bond betweenthe end portion of the inner liner 1 and the sealing material 15; andthe surfaces of the hose coupling body 13 and the sealing material 15respectively. As best shown in FIGS. 2 a and 3 a, a steel or syntheticpolymer ring 25 carrying an elastomeric sealing surface 22 is providedbetween an inner surface of the hose coupling body 13 and the innerlayer 1 of the flexible hose. This performs the dual functions of: (ii)preventing epoxy resin, introduced via the end caps 12, from enteringthe sealing area; and (ii) providing a compressive force to the layersbetween it and the inner sleeve 6 (i.e. via the inner liner 1 and thereinforcement material 2, if present).

For some types of sealing material 15, complete bonding between therespective surfaces within the sealing area 3 necessitates coating themwith a tie layer 14 before introducing the sealing material 15. The tielayer may be applied using conventional electrostatic coatingtechniques. Application of a tie layer may also add thermal insulationand mechanical strength to the connection within the sealing area 3.

In one embodiment, the sealing material 15 comprises a non-elastomericsemi-crystalline thermoplastic material such as an injection gradepolyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA) or a cross-linkedpolyethylene (PEX). In one embodiment, the sealing material 15, theinner liner 1 and the tie layer 14 each comprise a non-elastomericsemi-crystalline thermoplastic material. Ideally, the inner liner 1, thetie layer 14, and the sealing material 15 are formed from the samenon-elastomeric semi-crystalline thermoplastic material so as to createa single homogeneous polymer structure providing the best possiblechemical bond between the hose coupling body 13 and the inner liner 1within the sealing area 15.

The homogeneous polymer structure, e.g. based on the PVDF, PFA or PEXmaterials discussed above, will be substantially liquid impervious at apressure difference of the order of 5-10 bar. Consequently, anyreinforcement material 2 embedded within the inner liner 1 is protectedfrom corrosion. If the selected polymer structure is formed from a moreliquid permeable thermoplastic material then a fibre-based reinforcementmaterial 2 (as described above) may be utilised as an alternative tosteel. Where fibre-based material is undesirable, galvanised steel wireor cable may be employed as a means of protecting against corrosion.

All adjacent layers of the flexible hose are permanently chemicallybonded to each other in a manner known in the art. However, in apreferred embodiment it is important that the bonding process employeddoes not affect the non-bonded character of the reinforcement material 2within the flexible hose's inner liner 1. For example, the thermoplasticmaterial, e.g. PEX, may become cross-linked upon adding thereinforcement material 2.

The thermoplastic material of the inner liner 1 is permanently and fullychemically bonded to the surrounding rubber encased armour layers 9, 10.Consequently, shear deformation of the thermoplastic material of theinner liner 1 during bending and the application of combined loads maybe minimised. The PVDF, PFA or PEX materials discussed above havesufficient bonding and mechanical properties for high pressureapplications. If more inert and temperature resistant materials likepartially or fully fluorinated thermoplastics are employed, additionalproduction steps may be required to obtain full bonding. The term fullbonding is to be understood as meaning that either the mechanicalstrength limit of the elastomer rubber or that of the thermoplasticlayer is exceeded before the bond is broken. Since deformation andcompound loadings on a fully bonded pipe are taken up by both the innerliner 1 and the surrounding rubber encased armour layers 9, 10, thishelps to avoid known failure mechanisms and provides a significantperformance improvement in flexible hoses.

The external layers of the flexible hose surrounding the rubber encasedarmour layers 9, 10 comprise an anti-wear layer 17 and an outer cover18. These layers may be applied in the form of tapes and may compriseuni-directional, hi-directional or multi-directional reinforcementmaterial selected from one or more of the types already described above.The external layers may be over-extruded with a final thermoplasticlayer. For example, an impact resistant layer 19 in the form of a UHmwPE(ultra high molecular weight polyethylene) tape may be applied toprovide extra impact resistance and anti-wear characteristics. Analternative arrangement (shown in FIG. 8 b) may employ fibre reinforcedor hybrid steel/fibre fabric layers 26 in addition to, or instead of,tapes as an impact resistant layer. The external layers extend over thecoupling body 13 of the attached hose coupling.

An alternative arrangement for the external layer of the flexible hoseis shown in FIG. 5 whereby stainless steel interlock 21 is employed overan intermediate rubber cushion layer 20. This arrangement may be moresusceptible to damage within the moon pool area of a drillship orplatform than the alternative arrangement shown in FIG. 1.

An alternative manner of effecting a sealed connection between a hoseand a metallic coupling member will now be described with reference toFIGS. 6 to 12 b. FIG. 6 is a cross-sectional schematic view showing theconstituent layers of a hose which is substantially similar to thatillustrated in FIGS. 1 and 5. The constituent layers have beenprogressively stripped back towards the free end of the hose (i.e. atthe left hand side of FIG. 6) in preparation for fitting a hose couplingthereto in the manner described below.

The innermost layer of the flexible hose is a semi-crystalline polymerinner liner 1′ within which is embedded a reinforcement material 2′. Theinner liner 1′ is exposed at the free end of the hose and formed with anangled chamfer at its distal end which is complimentary in shape to anannular seat formed in the hose coupling 13′ (see the left hand side ofthe recess in FIGS. 11 a to 12 b). The inner liner 1′ may be formed fromany suitable type of semi crystalline thermoplastic, e.g. polymersderived from polyolefins as already described above with reference tothe embodiment of FIG. 1. The various layers which surround the innerliner 1′ are also described above with reference to the embodiment ofFIG. 1 and so need not be replicated here. However, as shown in FIGS. 6to 12 b, it is possible to remove the fabric layer 8 (shown in theembodiment of FIGS. 1 to 5) because the inner reinforcement 2′ can bedesigned to take up its structural function.

FIG. 7 shows a meltable sealing ring 23 which is slidably mounted on theexposed portion of the inner liner 1′ at the free end of the hose. Themeltable sealing ring 23 is a hybrid of semi-crystalline thermoplasticmaterial (preferably the same type as the inner liner) and metallicparticles selected from one or more the group comprising: fibres, coarsegrains, chips, or fine powder. The particles may be provided as amixture of different sizes to ensure an even distribution throughout thesolid meltable seal.

FIG. 8 a shows an annular hose coupling 13′ which has been push-fittedover the free end of the hose and properly aligned with the centrallongitudinal axis 100′. The hose coupling 13′ may be bonded to thestripped back layers of the flexible hose. This is achieved in a knownmanner by first heating the hose coupling 13′ (e.g. by means of aninduction coil) and introducing an epoxy resin through the end caps 12′.In order to prevent epoxy resin from entering into the sealing area, ametal or polymer ring 25′ carrying an elastomer sealing surface 22′ ismounted above the inner liner 1′ adjacent to the steel sleeve 7′. Theinternal diameter of the annular hose coupling 13′ increases in agenerally stepwise fashion from left to right as viewed in FIG. 8 a. Arecessed portion 3′ is provided at one end of the body of the hosecoupling 13′ nearest its narrowest internal diameter and defines asealing area.

The term “recessed portion” is to be understood in this context asdefining the inner enlarged diameter space bounded by the hose couplingbody and the inner liner 1′ of the flexible hose, i.e. including thevolume within which the solid meltable sealing ring 23 is seated. Theradial passage closed by the end cap 5′ is initially empty as shown moreclearly in FIG. 11 a. A nipple connector 4′ is provided inside thispassage to allow connection of a vacuum hose. The recessed portion maybe provided with an annular seat within which an end portion of thesolid meltable sealing ring 23 may be received (see the left hand sideof the recessed portion 23′ in FIGS. 8 to 12 b). This ensures a securemechanical lock between the annular hose coupling 13′ and the meltablesealing ring 23 prior to it being heated as described below.

FIG. 8 b is similar to FIG. 8 a but shows an alternative arrangementwhereby the meltable sealing ring 23′ is L-shaped in cross-section so asto extend over both the outer surface and the distal end of the innerliner 1′ at the free end of the hose. This arrangement is shown in moredetail in FIGS. 12 a and 12 b prior to, and after, activation of theinduction heater respectively.

FIG. 9 shows the same arrangement as FIG. 8 a whereby a supportingmember—in the form of a sealed silicone rubber hose incorporating aheatable induction coil—has been introduced beneath the inner liner 1′.In use, the sealed silicone rubber hose is inflated using an air supplyline 29 so as to apply a radial supporting pressure against thecylindrical inner wall of the inner liner 1′. Before and/or duringactivation of the heatable induction coil via electrical connections 28,substantially all air is removed from the recessed portion 3′. Bymaintaining vacuum conditions through the nipple connector 4′ within therecessed portion 3′ when the heatable induction coil is activated, allair bubbles are removed. The heating process continues until the solidmeltable sealing ring 23 becomes molten and increases in volume to fillthe recessed portion 3′ to a predetermined level as shown more clearlyin FIG. 11 b. This can be visually verified by checking the level of thesealing material through the end cap 5′. The duration and temperature ofheating will vary depending upon hose design and material choices.During this process, the inflated rubber hose ensures that the curedseal is correctly aligned.

A tie layer 14′ may be applied to the inner surface of the hose coupling13′ to provide a more reliable cohesive bond between the sealingmaterial and the metallic (e.g. steel) hose coupling. The choice of tielayer 14′ will vary depending upon the chemical make-up of thethermoplastic material used in the sealing material. The cohesive bond,between the sealing material and the surface of the hose coupling 13′within the sealing area, must be able to withstand the tendency for theinner liner to creep under high temperatures and/or pressures.

FIG. 10 is a cross-sectional schematic view corresponding to FIG. 8 bnow showing the establishment of chemical bond in the sealing area afterremoval of the sealed silicone rubber hose incorporating a heatableinduction coil as shown in FIG. 9.

It will be appreciated that the various embodiments of the presentinvention provide a number of advantages over existing arrangements forconnecting a flexible hose to a hose coupling. Most significantly, byproviding a non-elastomeric semi crystalline sealing material within thesealing area which is the same (or chemically similar) as that of theinner liner of the flexible hose, a homogeneous polymer structureextends from the flexible hose all the way into the hose coupling, i.e.the liner becomes the seal and the seal is the liner. This structureprovides a moisture-proof and gas-tight barrier more capable ofwithstanding harsh production environments than known prior artproducts.

Also, by embedding reinforcement material within the inner liner layerof the flexible hose, its connection with a hose coupling can be furtherstrengthened and improved. The integration of a reinforcement materialinto the inner liner layer closer to the core of the flexible hose makesthe bonded hose stronger and thus enables downscaling, if desired, ofthe outer armour layers. For example, the number of rubber outerreinforcement plies or the size thereof may be reduced. Consequently, itbecomes possible to achieve a more lightweight and/or flexible hosesystem. A properly designed reinforced inner layer can also replace theneed for an inner carcass because the supporting function is nowincorporated within the inner liner layer itself.

The embodiment of FIGS. 6 to 11 b provides the further advantage ofeliminating all air pockets from the sealing area. This arrangement alsoobviates the need for inserting the inner cylindrical supporting sleeve6 shown in FIGS. 1 to 3 and 5. The process of expanding the sleeve toswage the overlying sealing area is also eliminated. Instead, the innerliner 1′ of the flexible hose becomes part of the seal and so theprocess steps are significantly simplified and shortened.

The various embodiments of the present invention provide a sealingarrangement that overcomes, or at least ameliorates, one or more of thefollowing problems associated with elastomeric seals. Firstly, hightemperatures cause softening of elastomers which results in an increasedrate of liquid/gas diffusion, thus accelerating chemical degradation.This temperature-related issue can arise independently of high pressureconsiderations, although of course high pressures will furtherexacerbate the problem.

Modifications and improvements may be made to the foregoing withoutdeparting from the scope of the invention as defined by the accompanyingclaims. For example, a possible alternative to the aforementionedmeltable seal is a susceptor tape which could be wound around the outersurface of the flexible hose and its liner prior to fitting of the hosecoupling.

1-38. (canceled)
 39. An elastomeric flexible hose for the transportationof high pressure and/or temperature hydrocarbon liquids or gases, theelastomeric flexible hose comprising: (i) a semi-crystallinethermoplastic inner liner layer; (ii) an armour layer surrounding theinner liner layer at an end of the flexible hose; (iii) a hose couplingdisposed at the end of the hose and surrounding the armour layer; (iv) asealing area defined by a recessed portion of the hose coupling; (v) asemi-crystalline thermoplastic sealing material, or a cross-linkedelastomeric sealing material, disposed in the sealing area; and whereina portion of the inner liner layer at said hose end extends into thesealing area and is bonded to the sealing material; and wherein areinforcement material is provided wholly within the inner liner layerand further in that the inner liner layer is bonded to the inner surfaceof the hose coupling by a tie layer.
 40. The flexible hose according toclaim 39, wherein the reinforcement material is not bonded to thesemi-crystalline thermoplastic material.
 41. The flexible hose accordingto claim 39, wherein the reinforcement material comprises helicallywound steel cord and/or steel wires.
 42. The flexible hose according toclaim 41, wherein two or more separate helically wound steel cord and/orsteel wires are arranged in an interlocking fashion.
 43. The flexiblehose according to claim 39, wherein the reinforcement material isarranged within the inner liner layer in a wound fashion at an angle ofbetween 25 degrees and 85 degrees relative to the longitudinal axis ofthe flexible hose.
 44. The flexible hose according to claim 39, whereinthe reinforcement material comprises one or more fibre strands and/orrovings selected from the group consisting of glass fibres, carbonfibres, UHmwPE (ultra high molecular weight polyethylene) fibres, andaramid fibres.
 45. The flexible hose according to claim 39, wherein anelectrical heating element is provided within the inner liner layer. 46.The flexible hose according to claim 39, wherein a cylindrical sleevemember is disposed beneath the inner liner at the end of the flexiblehose and cooperates with the hose coupling proximate the sealing area tosupport a portion of the inner liner layer which extends into thesealing area.
 47. The flexible hose according to claim 39, wherein thesealing material is provided as an injectable fluid or molten syntheticpolymer.
 48. The flexible hose according to claim 39, wherein thesealing material is provided as a solid meltable seal.
 49. The flexiblehose according to claim 48, wherein the solid meltable seal comprisesmetallic particles selected from the group consisting of fibres, coarsegrains, chips, and fine powder.
 50. The flexible hose according to claim49, wherein different sizes of metallic particles are distributedthroughout the solid meltable seal.
 51. The flexible hose according toclaim 39, wherein the inner liner layer is coupled to the hose couplingby a crimped or swaged connection.
 52. The flexible hose according toclaim 39, wherein all adjacent layers of the flexible hose are partiallyor fully bonded in a permanent connection.
 53. The flexible hoseaccording to claim 39, wherein an outer cover layer surrounds the armourlayer and comprises a semi-crystalline thermoplastic material.
 54. Theflexible hose according to claim 53, wherein a reinforcement material isprovided within the outer cover layer.
 55. The flexible hose accordingto claim 54, wherein the reinforcement material comprises one or morematerials selected from the group consisting of steel cord, steelstrands, fibre strands, and fibre rovings.
 56. The flexible hoseaccording to claim 55, wherein the fibre strands or rovings comprise oneor more fibres selected from the group consisting of glass fibres,carbon fibres, UHmwPE (ultra high molecular weight polyethylene) fibres,and aramid fibres.
 57. The flexible hose according to claim 54, whereinthe reinforcement material within the outer cover is aligned in auni-directional, bi-directional, or multi-directional manner.
 58. Theflexible hose according to claim 54, wherein the reinforcement materialwithin the outer cover layer is provided within a fabric or a pliedtape.
 59. The flexible hose according to claim 39, wherein a stainlesssteel interlock cover layer surrounds the exterior of the flexible hose.60. A method of manufacturing an elastomeric flexible hose for thetransportation of high pressure and/or temperature hydrocarbon liquidsor gases, the method comprising the steps of: (i) providing a hosecoupling comprising a recessed portion defining a sealing area; (ii)providing a hose comprising a semi-crystalline thermoplastic inner linerlayer, and an armour layer surrounding the inner liner layer at an endof the flexible hose; (iii) providing a semi-crystalline thermoplasticsealing material, or a cross-linked elastomeric sealing material, forintroduction into the sealing area; (iv) providing a reinforcementmaterial wholly within the inner liner layer; (v) providing a tie layerapplied to the inner surface of the hose coupling to bond the hosecoupling and the inner liner layer; (vi) fitting the pipe coupling tothe end of the hose; and (vii) establishing a permanent chemical bondwithin the sealing area between the hose end and the sealing material;and the hose coupling and the sealing material respectively.
 61. Themethod according to claim 60, wherein the step of establishing apermanent chemical bond within the sealing area involves introducing thesealing material into the sealing area by mounting a solid meltable sealproximate the hose end before fitting the hose coupling to the hose end.62. The method according to claim 61, wherein the step of fitting thehose coupling to the hose end is followed by the step of introducing asupporting member beneath an inner surface of said hose end, thesupporting member incorporating a heater which melts the solid meltableseal within the sealing area.
 63. The method according to claim 62,wherein the step of introducing the supporting member involves employingan inflatable supporting member which is temporarily inflated againstthe inner surface of said hose end whilst the permanent chemical bond isestablished.
 64. The method according to claim 62, wherein the step ofintroducing a supporting member is followed by permanently swaging itagainst the inner surface of said hose end.
 65. The method according toclaim 60, wherein the step of melting the solid meltable seal within thesealing area is accompanied by the step of applying a vacuum to removesubstantially all air from the sealing area.